The Lung as an Embattled Domain Against Inanimate Pollutants

Recruitment of Phagocytizing Cells into the Respiratory Tract as a Response to the Cytotoxic Action of Deposited Particles

“…Thus, the organism is able to limit AM recruitment, especially that of NL when an effective clearance can be assured at lower costs in cell resources. Such regulation of the response is even more expedient because recruitment of an unusually large number of cells to the free alveolar surface can, by creating hindrances to their draining through a considerably smaller surface of the acinus mouth (32), become by itself, not an elimination mechanism, but a cause of dust retention. For instance, when AM and NL recruitment was enhanced by the action of some biogenic stimulators (33) or of cold acclimatization (17), pulmonary dust retention increased.…”

Response of a phagocyte cell system to products of macrophage breakdown as a probable mechanism of alveolar phagocytosis adaptation to deposition of particles of different cytotoxicity.

“…A search for physiological agents which increase the resistance of AM to damage and thereby help to increase the clearance efficiency along with a decrease of cell expenditure on it is indicated. When we deal with damage by silica particles to macrophages such increase of resistance means also a decrease of the factor stimulating silicotic fibrogenesis (71,75,76) and a favorable influence on other elements of the silicosis pathogenesis connected with a specific cytotoxicity of these particles. Experimental data showing that muscle training may provide a similar favorable influence lead to possible perspectives of this approach.…”

“…One more positive feedback, shown in the same scheme, reflects the earlier proved (15) enhancement of alveolar macrophage degeneration caused by inhaled quartz in rats, which had, due to long-term excessive fat administration PO, an increased sudanophilic inclusion content in AM. (71). In fact, the hyperstimulation of the AM and NL recruitment by some biogenic preparations did not speed up, but rather slowed the elimination of 60Co particles injected intratracheally, although a more moderate stimulation gave a favorable effect (30).…”

Some aspects of the problem of individual predisposition to silicosis.

“…This results from two counterbalancing phenomena: deposition of inhaled particles in low airways and their clearance. A well known estimate of the mass of dust recovered from miners' lungs postmortem compared with the computed dust deposition is approximately 98 to 99% total efficiency of pulmonary dust clearance during a long period of underground work (7). This seemingly narrow range indicates that under identical dust exposures, one may expect up to a twofold difference between the masses of dust accumulated in the lungs.…”

“…At the same time, however, a reactivity shift is observed which is clearly excessive, as the highly cytotoxic quartz dust itself induces an intensive recruitment of AMs, and especially NLs, into lower airways and alveoli. It has long been known that such inordinate recruitment of cells to the free surface of the acinus creates prerequisites for cellular stasis in the respiratory bronchiole, and thus becomes one of the mechanisms of particle retention instead of clearance (7). An increase of such retention was observed with the response of alveolar phagocytosis, and especially the NL recruitment, when hyperstimulated with the prodigiosane (67).…”